Controller which adjusts clock frequency based on received symbol rate

Abstract

A system is disclosed that includes two or more network elements, each comprising a Precision Time Protocol (PTP) Hardware Clock (PHC) that is adjustable based, at least in part, on physical layer frequency information.

The invention claimed is: 
     
       1. A system, comprising:
 two or more network elements, each network element comprising a Precision Time Protocol (PTP) Hardware Clock (PHC) that is adjustable based, at least in part, on physical layer frequency information, wherein the physical layer frequency information is extracted from an RX symbol rate. 
 
     
     
       2. The system of  claim 1 , wherein at least one of the two or more network elements comprises a cellular network element. 
     
     
       3. The system of  claim 2 , wherein the two or more network elements comprise a first antenna and a second antenna. 
     
     
       4. The system of  claim 1 , wherein a switch extracts the physical layer frequency information to determine an ensemble time, and wherein the ensemble time is used to adjust the PHC's frequency and the PHC's TX symbol rate. 
     
     
       5. The system of  claim 4 , wherein the switch determines the ensemble time based on at least a first RX symbol rate received from at least a first network element and based on at least a second RX symbol rate received from at least a second network element. 
     
     
       6. The system of  claim 1 , wherein the two or more network elements belong to a subnetwork that includes a switch. 
     
     
       7. A system, comprising:
 two or more network elements, each network element comprising a Precision Time Protocol (PTP) Hardware Clock (PHC) that is adjustable based, at least in part, on physical layer frequency information, wherein at least one of the two or more network elements comprises a data center element belonging to a data center cluster. 
 
     
     
       8. The system of  claim 7 , wherein the data center element comprises a Top-of-Rack (ToR) switch. 
     
     
       9. A cellular network, comprising:
 a first cellular network element comprising a first Precision Time Protocol (PTP) Hardware Clock (PHC) that is adjustable based, at least in part, on physical layer frequency information; and 
 a second cellular network element comprising a second PHC that is adjustable based, at least in part, on the physical layer frequency information, wherein the physical layer frequency information is extracted from an RX symbol rate. 
 
     
     
       10. The cellular network of  claim 9 , wherein the RX symbol rate corresponds to an RX symbol rate of the first cellular network element, the second cellular network element, or both. 
     
     
       11. The cellular network of  claim 9 , further comprising a switch, wherein a local clock at the switch is adjusted based on a weighted average of two or more RX symbol rates, and wherein the local clock is used to align the first PHC and the second PHC. 
     
     
       12. The cellular network of  claim 9 , wherein the first cellular network element comprises a first antenna, and wherein the second cellular network element comprises a second antenna. 
     
     
       13. The cellular network of  claim 9 , wherein the first cellular network element and the second cellular network element belong to a common micro cell. 
     
     
       14. The cellular network of  claim 9 , wherein the physical layer frequency information is extracted from a difference between the RX symbol rate and a TX symbol rate or from a difference between the RX symbol rate and the PHC. 
     
     
       15. A data center, comprising:
 a first network element and a second network element, wherein the first network element comprises a first Precision Time Protocol (PTP) Hardware Clock (PHC) that is adjustable based, at least in part, on physical layer frequency information, and wherein the second network element comprises a second PHC that is adjustable based, at least in part, on the physical layer frequency information, wherein the physical layer frequency information is used to determine an ensemble time, and wherein the ensemble time is used to adjust the first PHC's frequency. 
 
     
     
       16. The data center of  claim 15 , wherein the first network element comprises a first Network Interface Controller (NIC), and wherein the second network element comprises a second NIC. 
     
     
       17. The data center of  claim 15 , wherein the physical layer frequency information is received from a switch. 
     
     
       18. The data center of  claim 17 , wherein the switch is external to a subnetwork containing the first network element and the second network element. 
     
     
       19. The data center of  claim 15 , wherein the physical layer frequency information is extracted from an RX symbol rate. 
     
     
       20. The data center of  claim 15 , wherein the ensemble time is used to adjust the second PHC's frequency. 
     
     
       21. The data center of  claim 15 , wherein the first and second network elements are connected in a back-to-back configuration. 
     
     
       22. The data center of  claim 15 , wherein the first and second network elements are connected in a ring topology.